1. Field of the Invention
This invention relates to a system for driving auxiliary equipments by an automobile engine, and, in particular, to an auxiliary equipment drive system for driving the auxiliary equipments by an engine crankshaft through a power transmission mechanism.
2. Description of Related Art
Automobile engines are equipped with various auxiliary devices or equipments, such as alternators, air conditioner compressors, oil pumps, and water pumps, etc., which are driven by means of belts and pulleys connected to an engine crankshaft. For example, Japanese Unexamined Patent Publication No. 61-93232 discloses a configuration for driving a mechanical super charger, which is one of the auxiliary equipments, by an output shaft of a stepless transmission which can transfers the rotation of the engine crankshaft at linearly varying speeds. Similarly, Japanese Unexamined Utility Model Publication No. 63-21736 discloses a configuration for driving a supercharger by a crankshaft through a belt and pulley mechanism. In this mechanism, the supercharger is provided on its input shaft with an input pulley and a disk pressed against the input pulley via a facing member by means of an urging mechanism. This urging mechanism allows the disk to slip relatively the pulley so as to absorb the input torque from the crankshaft to the supercharger when the supercharger is disabled to operate.
On the other hand, Japanese Unexamined Patent Publication No. 61-105342 discloses a compressor drive mechanism for driving a compressor, which is one of engine related auxiliary equipment, in two different way. This compressor drive mechanism includes a plurality of pulleys provided on a crankshaft, first and secondary pulleys which are coaxially attached to a drive shaft of compressor, and first and secondary idle pulleys provided between the first and secondary compressor pulleys and between the first and secondary crankshaft pulleys, and first and secondary electromagnetic clutches disposed between the first and secondary compressor pulleys and between the first and secondary idle pulleys, respectively, for engaging and disengaging the compressor pulleys and the idle pulleys. By locking or unlocking of the first and secondary electromagnetic clutches, the transmission path from the crankshaft pulley to the first and secondary compressor pulleys is changed in two different courses.
Some of engine related auxiliary equipment, such as a mechanical supercharger, is provided with helical gears, as a torque input shaft, which are in mesh with each other and are mounted on a pair of parallel drive shafts, In this instance, as the supercharger operates, each of the drive shafts sustains a thrust force and consequently, cause axial vibration or oscillation. Especially, in the case where the supercharger is provided with a body of relatively large mass, such as a clutch by which supercharger pulleys, mounted for relative rotation on the drive shaft and driven by the crankshaft, are mechanically connected and disconnected, vibration of the supercharger is increased with an accompanying increase in noise.
In the case where a clutch is provided to an auxiliary equipment usually mounted on an engine by means of brackets, such as a supercharger, an alternator and the like and as a result, there is caused an increase in the weight of the auxiliary equipment, shifting of the center of gravity of the engine or the overall distribution of weight on the engine is caused, so that the added equipment becomes yet another source of engine vibrations.